3.6.2 Server name indication

A common problem in HTTPS servers is the fact that the
TLS protocol is not aware of the hostname that a client
connects to, when the handshake procedure begins. For that reason the
TLS server has no way to know which certificate to send.

This extension solves that problem within the TLS protocol,
and allows a client to send the HTTP hostname before the handshake
begins within the first handshake packet. The functions
gnutls_server_name_set and gnutls_server_name_get can be
used to enable this extension, or to retrieve the name sent by a
client.